Humans and presumably animals have the ability to sense the relative positions of their limbs in space without visual cues, and it has long been thought that receptors in articular tissues provide the sensory inputs for this limb-position sense. However, recent evidence has seriously challenged this traditional view and suggests that muscle receptors may provide the sensory input for limb-position sense. The neural substrate for a static limb-position sense has not yet been established in animals, but in preliminary experiments, we found that the cat somatosensory thalamus tonic activity related to hindlimb joint angles and such activity was driven by receptors in muscles, but not in joints. In the proposed work, we will extend these preliminary findings and seek to determine whether muscle receptor inputs can provide reliable, accurate limb-position related signals to the somatosensory thalamus, and to determine what spinal pathways and central relays carry limb-position related information.